Alexandria police are searching for a man who sexually assaulted a 20-year-old woman after trying to rob her late Thursday night.

The suspect, described as a clean-shaven Hispanic man in his late 20s or early 30s, about 5-foot-7 and 150 pounds with short black hair, approached the woman as she walked near the intersection of Courtney Avenue and Van Dorn Street about 11:30 p.m. He drew a knife and demanded money, authorities said.

When the woman replied that she didn’t have any money, he grabbed and dragged her over a guardrail before pulling her into a clump of bushes and sexually assaulting her, police said.

The suspect fled north, toward South Pickett Street, after the attack. He was last seen wearing a dark brown T-shirt, blue jeans, tennis shoes and a pair of black, framed glasses.

The victim, a city resident, was not seriously injured, police said. Officials urge anyone with information about the attack to contact the department’s criminal investigations section at 703-746-6711. Witnesses may remain anonymous.

Authorities do not believe the assault is related to similar incidents near the Holmes Run Parkway area earlier this year.